(Invited) Synthesis and Properties of Fluorinated Cubanes

Abstract

Electron acceptor molecules play an important role in the design of organic functional materials. The electron acceptor molecules reported so far are limited to π-conjugated molecules, which stabilize the accepted electrons by delocalizing them in the extended π-orbitals. In contrast, in perfluorocubane, in which eight carbons of the box-shaped molecule are fluorinated, the eight σ* orbitals of the C-F bonds overlap inside the box and are expected to accept and stabilize electrons there.[1] Since perfluorocubane is expected to accept electrons by overlapping σ* orbitals, it will probably show different physical properties from those of π-conjugated electron acceptor molecules.In the present study, we have succeeded in introducing multiple fluorine atoms into the carbon of cubane derivatives by using an original synthetic technique using fluorine gas,[2] which cannot be used in conventional synthetic organic chemistry. Using this key reaction, perfluorocubane (1), heptafluorocubane (2), and hexafluorocubane (3) were synthesized. Electrochemical and spectroscopic measurements demonstrated that the electron affinity increased with increasing the number of fluorine atoms. Furthermore, the successful observation of perfluorocubane radical anion by ESR measurement will be reported.[1] Irikura, K. K. J. Phys. Chem. A 2008, 112, 983–988. [2] Okazoe, T. J. Fluorine Chem. 2015, 174, 120–131. Figure 1